This invention relates to countersinks.
Countersinks are most commonly made in one piece of high speed steel or solid carbide. The disdvantage of this type of tool is that grinding is required to resharpen the tool when it dulls. The tool is eventually consumed completely by grinding.
Another type of countersink utilizes carbide inserts, but these inserts are of a special nature unique to the tool, and consequently quite expensive. Because of the expense of these special inserts, they require sharpening as a matter of practicality as they dull.
A third type of countersink utilizes standard inexpensive indexable carbide inserts, but only in one position on the tool. Consequently this type of tool cannot handle a wide range of hole sizes.